In the default mode, it transmits a mail to an SMTP server (for example at a
free mail provider) which takes care of further delivery.
To use this program with your mail user agent (MUA), create a configuration
file with your mail account(s) and tell your MUA to call msmtp instead of
/usr/sbin/sendmail.

Features include:

Sendmail compatible interface (command line options and exit codes)

Support for multiple accounts

TLS/SSL support including client certificates

Many authentication methods

Support for Internationalized Domain Names (IDN)

Fast SMTP implementation using command pipelining

DSN (Delivery Status Notification) support

SOCKS proxy support

msmtp is free software;
you can redistribute it and/or modify it under the terms of the
GNU General Public License
as published by the Free Software Foundation; either version 3 of the
License, or (at your option) any later version.